Removal of all pre-v1.1 versions of PyUAVCAN from PyPI

I am going to pull all releases of PyUAVCAN from PyPI prior to v1.1.0.dev0 because currently, the Python ecosystem prefers older releases if they do not contain .dev in the tag.

If you do pip install pyuavcan you end up with an old version which is bad. Removal of older pre-release versions will make this behavior explicit and thus more manageable.

If there are objections, please speak up now.